1. Field of the Invention
The present invention relates to a method for the stabilization of rock masses and the related stabilization element used for the purpose.
More particularly, the present invention relates to a method for the stabilization of rock masses in correspondence of the vault and/or sides of tunnels obtained by drilling.
2. Description of the Prior Art
As is known, in the construction of roads or railways it is often necessary to drill the ground, creating a tunnel, when a natural obstacle is found, constituted, for instance, by a mount relief or a rock spur. According to the nature of the grounds gone through, tunnels are provided with lining of various kinds and the just excavated passages are reinforced and stabilized by means of provisional supports. At present, for the consolidation of tunnels tubular elements of a remarkable length and close front are widespread; said elements are inserted into corresponding holes drilled in the rock by means of special rock-boring machines. In said tubular elements, the fluid determines the elastic deformation of the tubes, which adhere to the hole walls, following their substantially irregular profile.
Said known system of rock mass consolidation has several drawbacks associated especially to the high cost of the equipment used for the deformation of the tubular elements. Besides, said deformation is unavoidably limited and requires therefore the use of a high number of tubular elements to realize an adequate consolidation of the rock mass. The same elastic deformation of the elements reduces the resistance effect of the same, especially in correspondence of the most expanded zones; therefore, the system as a whole is not suitable for all kinds of grounds.
According to another technique of the known art, the consolidation of rock masses is obtained by means of untreated steel rods which are inserted into holes drilled in the rock mass; sideways of the bars, two tubes are placed, respectively for the injection and the bleed of consolidation mortar. This system has a main drawback associated to the weight of the rods, which, besides, do not show a high rigidity because of their great weight. As a consequence, the same rods enter with difficulty the holes drilled in the rock. Besides, this technique involves necessarily the use of two tubes to be placed near each rod.
Therefore, also this system is unsatisfactory because of both the obtained effect and the cost and complexity of the operations and the apparatuses.